Department of Radiotherapy, Ghent University Hospital, De Pintelaan, Ghent, Belgium.
Int J Radiat Oncol Biol Phys. 2012 Jun 1;83(2):696-703. doi: 10.1016/j.ijrobp.2011.07.037. Epub 2011 Dec 5.
To assess the accuracy of contour deformation and feasibility of dose summation applying deformable image coregistration in adaptive dose painting by numbers (DPBN) for head and neck cancer.
Data of 12 head-and-neck-cancer patients treated within a Phase I trial on adaptive (18)F-FDG positron emission tomography (PET)-guided DPBN were used. Each patient had two DPBN treatment plans: the initial plan was based on a pretreatment PET/CT scan; the second adapted plan was based on a PET/CT scan acquired after 8 fractions. The median prescription dose to the dose-painted volume was 30 Gy for both DPBN plans. To obtain deformed contours and dose distributions, pretreatment CT was deformed to per-treatment CT using deformable image coregistration. Deformed contours of regions of interest (ROI(def)) were visually inspected and, if necessary, adjusted (ROI(def_ad)) and both compared with manually redrawn ROIs (ROI(m)) using Jaccard (JI) and overlap indices (OI). Dose summation was done on the ROI(m), ROI(def_ad), or their unions with the ROI(def).
Almost all deformed ROIs were adjusted. The largest adjustment was made in patients with substantially regressing tumors: ROI(def) = 11.8 ± 10.9 cm(3) vs. ROI(def_ad) = 5.9 ± 7.8 cm(3) vs. ROI(m) = 7.7 ± 7.2 cm(3) (p = 0.57). The swallowing structures were the most frequently adjusted ROIs with the lowest indices for the upper esophageal sphincter: JI = 0.3 (ROI(def)) and 0.4 (ROI(def_ad)); OI = 0.5 (both ROIs). The mandible needed the least adjustment with the highest indices: JI = 0.8 (both ROIs), OI = 0.9 (ROI(def)), and 1.0 (ROI(def_ad)). Summed doses differed non-significantly. There was a trend of higher doses in the targets and lower doses in the spinal cord when doses were summed on unions.
Visual inspection and adjustment were necessary for most ROIs. Fast automatic ROI propagation followed by user-driven adjustment appears to be more efficient than labor-intensive de novo drawing. Dose summation using deformable image coregistration was feasible. Biological uncertainties of dose summation strategies warrant further investigation.
评估轮廓变形的准确性和剂量叠加的可行性，应用于头颈部癌症的自适应剂量绘画（DPBN）中的变形图像配准。
使用了 12 名在头颈部癌症 I 期试验中接受自适应（18）F-FDG 正电子发射断层扫描（PET）指导 DPBN 治疗的患者的数据。每位患者都有两个 DPBN 治疗计划：初始计划基于治疗前的 PET/CT 扫描；第二个适应性计划基于 8 次分割后的 PET/CT 扫描获得。两个 DPBN 计划的剂量到剂量绘画体积的中位数处方剂量为 30 Gy。为了获得变形轮廓和剂量分布，使用变形图像配准将预处理 CT 变形为每次治疗的 CT。通过视觉检查感兴趣区域（ROI(def))的变形轮廓，如果需要，调整（ROI(def_ad))并使用 Jaccard（JI）和重叠指数（OI）与手动重新绘制的 ROI（ROI(m))进行比较。在 ROI(m))、ROI(def_ad)或它们与 ROI(def)的并集上进行剂量叠加。
几乎所有变形的 ROI 都进行了调整。在肿瘤明显消退的患者中进行了最大的调整：ROI(def) = 11.8 ± 10.9 cm(3) vs. ROI(def_ad) = 5.9 ± 7.8 cm(3) vs. ROI(m) = 7.7 ± 7.2 cm(3)（p = 0.57）。吞咽结构是最常调整的 ROI，上食管括约肌的指数最低：JI = 0.3（ROI(def)) 和 0.4（ROI(def_ad)); OI = 0.5（两个 ROI）。下颌骨需要的调整最少，指数最高：JI = 0.8（两个 ROI），OI = 0.9（ROI(def))，1.0（ROI(def_ad))。剂量总和无显著差异。当在联合部位进行剂量叠加时，靶区的剂量有升高趋势，脊髓的剂量有降低趋势。
大多数 ROI 需要进行视觉检查和调整。快速自动 ROI 传播后，用户驱动的调整似乎比劳动密集型的从头开始绘制更有效。使用变形图像配准进行剂量叠加是可行的。剂量叠加策略的生物学不确定性需要进一步研究。
